1. Field
The following description relates to an organic light-emitting device.
2. Description of the Related Art
Organic light-emitting devices (OLEDs), which are self-emitting devices, have advantages such as wide viewing angles, excellent contrast, quick response, high brightness, and excellent driving voltage characteristics, and can provide multicolored images.
A typical OLED has a structure including a substrate, an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a cathode which are sequentially stacked on the substrate. The HTL, the EML, and the ETL are organic thin films formed of organic compounds.
An operating principle of an OLED having the above-described structure is as follows.
When a voltage is applied between the anode and the cathode, holes injected from the anode move to the EML via the HTL, and electrons injected from the cathode move to the EML via the ETL. The holes and electrons (carriers) recombine in the organic EML to generate excitons. When the excitons drop (e.g., transition) from an excited state to a ground state, light is emitted.
Since OLEDs are composed of organic materials, when they are combined with water molecules and oxygen, the characteristics of organic materials may deteriorate. Accordingly, encapsulation technology is used to prevent or reduce permeation of water molecules and oxygen into OLEDs.